Differences in cardiovascular risk in the general population of low and high altitude residents in Peru. HIGH Altitude CArdiovascular REsearch Latin America Population Study (HIGHCARE-LAPS)

Abstract Introduction Living at high altitude (HA) is associated with profound changes in cardiovascular physiology, mostly caused by chronic hypoxia. Available data from high income countries (Switzerland, Austria) suggest beneficial effects of moderate altitude residence in terms of cardiovascular risk. Little is known, however, about cardiovascular risk profile in long-term residents of higher altitudes from low-income countries. Aim To compare cardiovascular risk estimated with validated score in population-based samples of permanent residents of low and high-altitude communities in Peru. Methods Study participants (adults permanently residing at either low or high altitude) were recruited by sex- and age-stratified random multistage cluster sampling from the general population of urban areas at different altitudes in Peru (lowlanders: <500 m above sea level, highlanders: cities at 3287 m, 3824 m and 4330 m). For all participants questionnaire-based information, conventional blood pressure (BP; 3 seated measurements with a validated oscillometric device) and laboratory variables were obtained. Based on the collected data atherosclerotic cardiovascular disease (ASCVD) risk was estimated according to Pooled Cohort Equations (PCE, previously calibrated in South American population). Participants below 40 years of age, with ASVCD history, with LDL-C≥190 mg/dL or on LDL-C lowering therapy were excluded from this analysis. Results The analysis included 146 lowlanders and 373 highlanders, most of whom had low 10-year ASVCD risk, with the median estimated risk being significantly higher among lowlanders. Comparisons between the groups in terms of principal variables of interest are reported in the Table. The highlanders were slightly younger, had lower BMI, conventional BP, HDL cholesterol, lower prevalence of antihypertensive medication and of diabetes, and higher heart rate. In a multivariable model the difference in ASCVD risk between lowlanders and highlanders was significant (p=0.0009) after adjusting for BMI and socio-economic variables but not after systolic BP was included in the model (p=0.800). Conclusions Residence at HA is associated with a lower estimated ASCVD risk in the general population of Peru, mainly because of lower BP levels. Considering that the prognostic value of cardiovascular risk estimates in highland populations is unknown, longitudinal cohort studies would be required to assess whether this finding is associated with a lower rate of cardiovascular events.